How can I get 0x800704cf with Win 10 when linking to my NAS Server?

I have an NAS Server with FreeNAS v 9.3 . It worked properly with in 8.1 before and after upgrading to Win 10 I always get error code 0x800704cf and no link possible. With my Laptop, still on Win 7 the connection is no problem at all, means on the NAS side everything runs well.